Apparatus for the production of calcium carbid.



No. 809,842. PATENTED JAN. 9, 1906. E. F. PRICE, G. E. COX .& J. G.MARSHALL.

APPARATUS F OB THE PRODUCTION OF CALCIUM GARBID.

APPLICATION FILED GCT.19.1904.

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'6 AZ JIIM flaw mo Jixiys- No. 809,842. PATENTED JAN. 9, 1906.

E. F. PRICE, G. E. COX & J. G. MARSHALL. APPARATUS FOR THE PRODUCTION OFCALCIUM OARBID.

APPLICATION FILED OCT. 19.1904.

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Men/$075 WWW 7 3 UNITED STATES PATENT OFFICE.

EDGAR F. PRICE, GEORGE E. COX, AND JAMES G. MARSHALL, OF NIAGARA FALLS,NEW YORK, ASSIGNORS TO UNION CARBIDE COMPANY, OF NIAGARA FALLS, NEWYORK, A CORPORATION OF VIRGINIA.

APPARATUS FOR THE PRODUCTION OF CALCIUM CARBID- Specification of LettersPatent.

Patented Jan. 9, 1906.

.6 Application filed October 19, 1904. Serial No. 229,169.

To all whom, it Wmy concern:

Be it known that we, EDGAR F. PRICE, GEORGE E. Cox, and JAMES G.MARsHALL, citizens of the United States, residing at Niagara Falls, inthe county of Niagara and State of New York, have invented certain newand useful Improvements in Apparatus for the Production of CalciumCarbid, of which the following is a specification.

The manufacture of calcium carbid has heretofore been carried out inelectric furnaces employing electrodes of any usual car boncompositionfor example, a molded and baked mixture of ground coke andtar. Graphite electrodes have been considered undesirable andimpracticable for this use on account of their high cost, theiroxidizability, and especially their high specific-heat conductivity.Graphite electrodes of the same dimensions now cost about three times asmuch as the carbon electrodes heretofore used in carbid-furnaces. Ifsuch graphite electrodes were substituted for the carbon electrodes,they would transmit so much heat from the Zone of reduction to the usualiron holders that the latter would soon be destroyed. If injury of theholders were delayed by the use of special cooling means, neverthelesson account of their high temperature the life of the graphite electrodeswould be shorter than that of the ordinary carbon ones. Any decrease inthe diameter of the graphite rods to decrease their cost andheat-carrying capacity would render their life much shorter than that ofthe carbon rods. The cost of electrodes is one of the importantfactorsin the cost of carbid, and the specified reasons have prevented the useof graphite, notwithstanding its high electrical conductivity, uniformcomposition, and the ease with which it can be machined. We have nowdetermined certain conditions under which graphite rods can be used forthe production of calcium carbid without materially increasing the costof the electrodes, while their life is so greatly lengthened that thefinal cost is reduced to a minimum. We have first reduced thecrosssection of the electrode-rods in proportion to the increaseddensity of the current which the graphite will carry without beingunduly heated. This change suitably decreases the heat conductivity ofthe rods, but renders them mechanically weak, so that they would breakin the furnace. They would also soon be destroyed. by oxidation. WVehave therefore placed a strong body of refractory cement of relativelyhigh resistance between and around the graphite rods, thus mechanicallysupporting them and protecting them from oxidation. Ne have alsoprovided efficient means for cooling the metal holders.

The invention will be readily understood by reference to theaccompanying drawings, in which- Figure 1 is a vertical transversesection through a pair of electrodes supported in the hood of acalciumcarbid furnace, the section being taken on the line I I of Fig.2. Fig. 2 is a horizontal section through the top plate of the hood,taken on the line II II of Fig. 1. Fig. 3 is a vertical longitudinalsection through one of the electrode-holders, showing a metal sheath insection upon one of the electrode-rods. Fig. 4 is a side elevation of anelectrode, partly in section, to show the filling of refractory cementand the support of foraminous metal; and Fig. 5 is a horizontal sectionthrough the electrode on the line V V of Fig. 4.

The electrode-holder consists of a head 1, of cast-iron, having aperforated lug 2,which serves asa terminal and support for theelectrode. I/Vithin the holder is a water-chamber 3, having supply anddischarge pipes 4 5. A longitudinal depending baffle 6 extends from thetop nearly to the bottom of the water-chamber. A number of threadedopenings 7 extend through the lower wall of the head 1, and each ofthese openings receives a nipple 8. An electrode-socket 9 is threadedinto the lower end of each nipple and projects upward within the nipple,leaving an intermediate space for the circulation of water. The upperend of each graphite electrode-rod 10 is threaded and screwed into oneof these sockets, making good electrical contact with it. The length ofthe depending nipples makes it possible to use short electrode-rods,thus decreasing the length of the stubs which remain when the rods havebeen consumed as far aspossible and enabling a greater percentage of thelength to be utilized. The stubs may also be threaded together and usedfor the electrode-rods.

The wellknown Horry furnace for the production of calcium carbid employsa hood which receives the electrodes and depends into the workingchamber of the furnace. One of these hoods 11 is shown in section inFig. 1, depending into the working chamber 12 of the furnace. A pair ofelectrodes is shown, the holder of each electrode extending through anopening 13 in the top plate 1 1 of the hood. The space between theelectrode-holders and the top plate is filled with a luting 14, ofrefractory cement. A pipe 15 for supplying the furnace charge of limeand coke opens through the top plate at the rear and a pipe 16 forremoving the waste gases leads from the top plate at the front. Toassist in removing the heat from the electrodeholders, as well as toreduce the temperature of the hood itself, it has been found desirableto make the top plate 11 of cast-iron with an internal water-chamber 17,having a supplypipe 18 and a discharge-pipe 19.

One or more of the electrode-rods may be inclosed in a closely-fittingiron sheath 20, as shown in Fig. 3. The graphite rod is preferablycoated with tar before being pushed into the sleeve. Air is thusentirely excluded from the surface of the rod. The upper end of thesleeve 20 may be threaded into a counterbore 21 in the lower end of thecorresponding socket 9. The electrode-rods are mechanically reinforcedand strengthened and at the same time protected from oxidation by a bodyof refractory cement of relatively high resistance, which is filledbetween and around the rods. This cement may consist of ordinaryasbestos or furnace cement mixed with ground bituminous coal andsiloxicon. To strengthen the body of cement and prevent it from scalingoff from the rods when heated, a support 23, of thin foraminous metal,such as expanded iron, is wrapped around the rods and plastered overwith the cement.

This invention makes it possible to use graphite electrodes in acalcium-carbid furnace. The greater cost of the graphite is 011 set bythe reduction in the cross-section and length of the electrode-rods. Therods of reduced cross-section are efliciently strengthened and protectedfrom oxidation by the reinforcing-body of cement. The waterc'ooledholders and electrode-sockets prevent the metal parts from burning out,and the long socket-nipples decrease the stub waste of the electrodes.

The claims of this application are specifically limited to theproduction of calcium carbid, claims for the electrodes andelectrode-holders for general use being presented in our application,Serial N 0. 177,607, filed October 19, 1903.

We claim-- 7 1. In an electric furnace for the production of calciumcarbid, and in combination with a feed-supply of lime and carbon,electrodes consisting of graphite rods of reduced crosssection, meansfor supplying to the electrodes an electric current of suflicientamperage to give a high current density in the elec trodes and effectthe reduction of the charge, means for substantially excluding oxidizinggases within the charge from the sides of said rods and means forwithdrawing heat from the ends of the electrodes remote from the zone ofreduction, as set forth.

2. In an electric furnace for the production of calcium carbid, and incombination with a -feedsupply of lime and carbon, electrodes eachconsisting of spaced graphite rods, means for supplying to theelectrodes an electric current of sufficient amperage to give a highcurrent density in the electrodes and effect the reduction of thecharge, a jacket surrounding the electrode-rods for excluding gasestherefrom, and means for withdrawing heat from the ends of theelectrodes remote from the zone of reduction, as set forth.

3. In an electric furnace for the production of calcium carbid, and incombination with a feed-supply of lime and carbon, electrodes consistingof graphite rods of reduced crosssection, means for supplying to theelectrodes an electric current of suflicient amperage to give a highcurrent density in the electrodes and effect the reduction of thecharge, means for substantially excluding oxidizing gases from the sidesof the rods and for supporting them against breakage, and means forwithdrawing heat from the ends of the electrodes remote from the zone ofreduction, as set forth.

4. In an electric furnace for the production of calcium carbid, and incombination with a feed-supply of lime and carbon, electrodes consistingof graphite rods of reduced crosssection, means for supplying to theelectrodes an electric current of sufficient amperage to give a highcurrent density in the electrodes and effect the reduction of thecharge, a reinforcing and protecting body of relatively high resistancesurrounding said rods, and means for withdrawing heat from the ends ofthe electrodes remote from the zone of reduction, as set forth.

In testimony whereof we aflix our signatures in presence of twowitnesses EDGAR E. PRICE. GEORGE E. cox. JAMES G. MARSHALL itnesses A.A. MosHER, C. E. BILLINGs.

